Sealing device for a gear box

ABSTRACT

A sealing device for a gear box includes a box having a hole defined through a wall thereof and a shaft having a first end rotatably engaged with an inside of the box and a second end of the shaft is supported by a bearing which is received in a frame engaged with the hole of the box. A cap is connected to an end of the frame in the box and mounted to the second end of the shaft. A space is defined between a skirt and a protrusion of the cap so as to receive a seal therein. The seal has a flexible plate which is engaged with the end of the frame in the box. The flexible plate effectively prevents oil in the box from entering a gap between the bearing and the frame when the shaft is not rotated.

FIELD OF THE INVENTION

[0001] The present invention relates to a sealing device for a gear boxand includes a cap mounted to the shaft and the cap includes a receivingspace in which a seal is engaged. The seal prevents oil flowing into thegap between the bearing frame and the bearing.

BACKGROUND OF THE INVENTION

[0002] A conventional gear box is shown in FIG. 4 and generally includesa worm rod 20 rotatably received in the box 10 and one end of the wormrod 20 is rotatably connected to an inside of the gear box 10 and theother end of the worm rod 20 extends from an opening 11 of the gear box10. A bearing 60 is engaged with the opening 11 of the gear box 10 andsecond end of the worm rod 20 is supported by the bearing 60 andconnected with a driving shaft. A seal 61 is mounted to the second endof the worm rod 20 and prevents oil in the gear box 10 from leakage. Inorder to have a better result of sealing, the seal 61 has to securelymounted to the worm rod 20 while allowing the worm rod 20 to rotate asdesired. The friction between the seal 61 and the second end of the wormrod 20 is too large and consumes the energy for driving the worm rod 20.The seal 61 is replaced frequently because of the wearing. FIG. 5 showsan improved sealing device which includes a plate 80 mounted to therotatable shaft 72 in the gear box 70 and the plate 80 has a flange 81which is mounted to a flange 71 extending from an inside of the box 70.A bearing 90 is engaged with a hole defined through the wall of the box70 and is covered by the plate 80. A seal 91 is mounted to an end of theshaft 72 which extends from the hole of the box 70. The plate 80 splitaway the oil in the box 70 to prevent the oil from entering the gapsbetween an inner periphery of the hole and the bearing 90 when therotatable shaft 72 is rotated. The arrangement of the plate 80 allowsthe seal 91 not to be necessarily secured to the rotatable shaft 72 sothat the friction between the rotatable shaft 72 and the seal 91 is lessthan that in the example shown in FIG. 4. This result of sealing for theplate 81 is not satisfied when the rotatable shaft 72 is not rotated,because the oil may flow over the flange 81 of the plate 80 and thenenter into the bearing 90 and the gap between the bearing 90 and theinner periphery of the hole of the box 70.

[0003] The present invention intends to provide a sealing device for agear box wherein a seal is received in a space of a cap so as to preventthe oil flowing into the gap between the bearing and the frame even whenthe worm rod is not rotated.

SUMMARY OF THE INVENTION

[0004] In accordance with one aspect of the present invention, there isprovided a sealing device for a gear box and the device comprises a boxhaving a hole defined through a wall thereof and a shaft has a first endrotatably engaged with an inside of the box and a second end of theshaft extends through the hole. A frame is engaged with the hole of thebox and a bearing is engaged in the frame. The bearing is mounted to thesecond end of the shaft. A cap is connected to an end of the frame inthe box and a seal is located in an inside of the cap. The seal has aflexible plate which is engaged with the end of the frame in the box.

[0005] The present invention will become more obvious from the followingdescription when taken in connection with the accompanying drawingswhich show, for purposes of illustration only, a preferred embodiment inaccordance with the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0006]FIG. 1 is an exploded view to show the sealing device of thepresent invention;

[0007]FIG. 2 is a side cross sectional view to show the sealing deviceof the present invention;

[0008]FIG. 3 is an enlarged view to show the flexible plate of the sealcontacting the end of the frame in the box;

[0009]FIG. 4 is a side cross sectional view of a first conventionalsealing device for a gear box, and

[0010]FIG. 5 is a side cross sectional view of a second conventionalsealing device for a gear box.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0011] Referring to FIGS. 1 and 2, the sealing device for a gear box ofthe present invention comprises a box 10 having a hole 11 definedthrough a wall thereof and a shaft 20 such as a worm rod, has a firstend 21 rotatably engaged with an inside of the box 10 and a second end23 of the shaft 20 extends through the hole 11. The worm screws 22 ofthe shaft 20 are engaged with a worm gear 80 and transfers the powerfrom the driving shaft 70 to the worm gear 80. A frame 50 is engagedwith the hole 11 of the box 10 and a bearing 60 is engaged in a hole 51of the frame 50. The bearing 60 is mounted to the second end 23 of theshaft 20.

[0012] A cap 30 has a protrusion 31 extending from a side thereof and ahole is defined through the protrusion 31. The second end of the shaft20 extends through the hole of the protrusion 31. A lip extends from aninner periphery of the hole of the cap 30 and the shaft 20 has a flange24 extending from an outer periphery thereof, the lip of the cap 30 isengaged with the flange 24 of the shaft 20. A skirt 32 extends from anouter periphery of the cap 30 and a recess 52 is defined in the end ofthe frame 50 in the box 10 so that an outer periphery of the skirt 32 ofthe cap 30 is engaged with the recess 52. A seal 40 is engaged betweenthe skirt 32 and the protrusion 31, and has a flexible plate 41 which isengaged with the end of the frame 50 in the box 10.

[0013] When the shaft 20 is rotated, the cap 30 is co-rotated with theshaft 20 and the oil is splashed away from the bearing 60 so that thepossibility of oil leakage is reduced to minimum. When the shaft 20 isnot rotated, referring to FIG. 3, the flexible plate 41 contacts theinside of the end of the frame 50 in the box 10 such that the oil isstopped by the flexible plate 41 to enter into the bearing 60.

[0014] While we have shown and described the embodiment in accordancewith the present invention, it should be clear to those skilled in theart that further embodiments may be made without departing from thescope of the present invention.

What is claimed is:
 1. A sealing device for a gear box, comprising: abox having a hole defined through a wall thereof and a shaft having afirst end rotatably engaged with an inside of the box and a second endof the shaft extending through the hole; a frame engaged with the holeof the box and a bearing engaged in the frame, the bearing mounted tothe second end of the shaft, and a cap connected to an end of the framein the box and a seal located in an inside of the cap, the seal having aflexible plate which is engaged with the end of the frame in the box. 2.The sealing device as claimed in claim 1, wherein the shaft has a flangeextending from an outer periphery thereof so as to be engaged with thecap.
 3. The sealing device as claimed in claim 1 further comprising arecess defined in the end of the frame in the box and an outer peripheryof the cap engaged with the recess.
 4. The sealing device as claimed inclaim 1 wherein the cap has a protrusion and a hole is defined throughthe protrusion, the second end of the shaft extends through the hole ofthe protrusion.
 5. The sealing device as claimed in claim 4, wherein thecap has a skirt extending from an outer periphery thereof and the sealis engaged between the skirt and the protrusion.